1. Field of the Invention
The present invention relates to an apparatus for ejecting droplets.
2. Description of Related Art
It is required that an ink-jet head for ejecting ink to a recording sheet should be able to eject fine ink droplets in order to realize a high-quality printing. Also required is a technique for ejecting fine droplets to an ejection object in order to form a fine wiring pattern on a substrate by ejecting a conductive paste, to form a high-resolution display by ejecting an organic luminescent material onto a substrate, to form a micro-optical device such as an optical waveguide by ejecting optical plastics onto a substrate, and the like.
In an ink-jet head, for example, when a diameter of a nozzle hole for ejecting ink is reduced, an ink droplet ejected therefrom becomes smaller to a certain extent. Also proposed is to control an ejection pulse signal which will be supplied to an actuator that causes an ink droplet to be ejected from a nozzle hole. Thereby, an ink droplet having an arbitrary size may be ejected from a nozzle hole. For example, Japanese Patent Unexamined Publication No. 7-285222 discloses an ink-jet recording apparatus which controls an ejection pulse signal so that a main droplet firstly ejected from a nozzle hole and a satellite droplet subsequently ejected may have the same weight. This ink-jet recording apparatus allows a resolution along a main scanning direction to be substantially doubled.